1. Field of the Invention
The present invention relates to a toner for a toner-jetting system wherein a toner-supporting member and a recording medium, such as paper and the like are maintained in a non-contact state, and a charged toner from the toner-supporting member is jettingly adhered to the recording medium in a direct manner to form an image.
2. Description of the Related Art
Conventionally, electrophotographic apparatuses have been generally used as apparatuses for copying (printing) images such as letters and graphics. However, in the electrophotographic apparatuses, an electrostatic latent image is formed on the surface of an image-supporting member (photosensitive member), and toner is allowed to adhere to the electrostatic latent image on the image-supporting member so as to visualize the electrostatic latent image, thereby temporarily forming an image; thereafter, the resulting toner image on the image supporting-member is transferred to a recording medium. Therefore, such a system makes the apparatus size bulky and the cost higher.
For this reason, a toner-jetting system (direct recording method) has been proposed in which: a recording electrode and a back electrode are placed face to face with a toner-supporting member; a recording medium such as paper is transported between the recording electrode and the back electrode; a voltage corresponding to an image signal is applied to the recording electrode so that an electrostatic force is exerted on the toner; and in accordance with the voltage-applied state, the toner from the toner-supporting member is jettingly adhered to the recording medium in a direct manner.
However, in such a toner-jetting system, when the toner flies from the toner-supporting member to the recording medium, the toner is forced to pass through a number of holes in the recording electrode, with the result that problems arise in which upon flying from the toner-supporting member to the recording medium, the toner adheres to the recording electrode (FPC stain), resulting in clogging in the holes of the recording electrode.
Moreover, the above-mentioned recording system also causes problems with image quality in the resulting images. For example, when dots are printed, a phenomenon tends to occur (referred to as "tailing") in which the dots are extended and distorted in the transporting direction of paper, or when lines are printed, a problem arises in which line edges become dull or the toner particles scatter on paper area between lines (problem with convergence). Moreover, another problem arises in which when the toner flies to the recording medium from the toner-supporting member, the toner is not separated from the toner supporting-member smoothly, resulting in a reduction in the image density (problem with separating property).